A fierce succession battle appears to be gripping the senior ranks of al-Qaida in the wake of the death of their leader, Osama bin Laden, pitting regional affiliates against the central "hardcore" of the organisation.

Reports from Pakistan have named an Egyptian former special forces officer known as Saif al-Adel as the acting leader of al-Qaida. Adel, who is in his late 40s, is a veteran militant who was close to Bin Laden in the 1990s. He was detained in Iran after fleeing Afghanistan following the ousting of the Taliban in 2001. According to Noman Benotman, a former Libyan militant now living in London, Adel was released from Iranian detention and returned to Pakistan last year.

The report in the News newspaper of Pakistan identified Adel as having been chosen as "interim leader" of al-Qaida after a meeting at "an undisclosed location". It said none of the sons of Osama bin Laden had shown willingness to take up a formal position within the organisation.

One of the 54-year-old al-Qaida leader's sons was killed in the raid on Abbottabad. Other sons have been groomed for leadership roles but are too young or inexperienced to command any real support.

If confirmed the appointment of Adel is a major blow to Bin Laden's close associate Ayman al-Zawahiri, the Egyptian extremist who has long been seen as the group's number two and key strategist.

Zawahiri is reported to have been given the role of director of external or international operations for the group. This would be something of a demotion for a man who was Bin Laden's closest associate and a major figure in his own right.

It could provide the first evidence of a major split within militant ranks. Senior al-Qaida-affiliated extremists in both Iraq and Yemen have already pledged their support for Zawahiri, 59, and may not accept the leadership of Adel.

"I tell our brothers in al-Qaida led by Ayman al-Zawahiri, go on with God's blessing and be glad that you have faithful brothers in the Islamic State of Iraq who are marching on the path of right," Abu Bakr al-Baghdadi, recently appointed head of the al-Qaida affiliated Islamic State of Iraq (ISI), said in a statement posted on the internet last week. Baghdadi is thought to have been named to his post by Zawahiri.

Rashad Mohammed Saeed Ismail, a senior Yemeni cleric who was close to Bin Laden, was quoted by the Yemen Times as saying: "Zawahiri is the best candidate."

Security sources have told the Guardian that until there is some kind of communication from verifiable al-Qaida sources it is impossible to be certain who will become overall leader.